1. Field of the Invention
The present invention relates to lithographic systems, and more particularly to supporting optical elements in lithographic systems.
2. Related Art
A lithographic apparatus is a machine that applies a desired pattern onto a substrate or part of a substrate. A lithographic apparatus can be used, for example, in the manufacture of flat panel displays, integrated circuits (ICs) and other devices involving fine structures. In a conventional apparatus, a patterning device, which is commonly referred to as a mask or a reticle, can be used to generate a circuit pattern corresponding to an individual layer of a flat panel display (or other device). This pattern can be transferred onto all or part of the substrate (e.g., a glass plate), by imaging onto a layer of radiation-sensitive material (e.g., photoresist) provided on the substrate.
Once the patterning device has patterned input illumination, the resulting illumination can be projected onto the substrate by one or more lenses. Displacements and/or deformations of the one or more lenses can cause errors in the patterned substrate. For example, vibrations or oscillations in an apparatus that supports the lenses can cause them to be displaced resulting in shifts or other errors in the pattern that is to be transferred onto the substrate. Furthermore, heat generated during the lithography process can lead to a deformation of the lenses causing a deformation of the pattern to be transferred onto the substrate.